/** The longest dep set of the sub-sequence s[0..idx]. */
public static BitSet longestDepSet(Sequence s, int idx) {
if (s.size() == 0) throw new IllegalArgumentException("size must be greater than 0.");
if (idx < 0 || idx >= s.size()) throw new IllegalArgumentException();
assert s.size() <= maxlength;
int max = -1;
int maxidx = -1;
for (int i = 0; i <= idx; i++) {
BitSet set = sets[i];
set.clear();
set.set(i);
lastuse[i] = i;
for (Variable invar : s.getInputs(i)) {
set.or(sets[lastuse[invar.index]]);
lastuse[invar.index] = i;
}
int size = set.cardinality();
if (size > max) {
max = size;
maxidx = i;
}
}
for (int i = 0; i < s.size(); i++) {
// System.out.println("@ " + sets[i]);
}
return sets[maxidx];
}
public static Set<Integer> predecessors(Sequence s, int idx) {
Set<Integer> ret = new LinkedHashSet<Integer>();
Set<Variable> depvars = new LinkedHashSet<Variable>(s.getInputs(idx));
for (int i = idx - 1; i >= 0; i--) {
boolean toadd = false;
if (depvars.contains(s.getVariable(i))) {
toadd = true;
} else {
for (Variable v : s.getInputs(i)) {
if (depvars.contains(v)) {
toadd = true;
break;
}
}
}
if (toadd) {
ret.add(i);
depvars.addAll(s.getInputs(i));
}
}
return ret;
}
public static Sequence predecessorSequence(Sequence s, int idx) {
List<Integer> indices = new ArrayList<Integer>(predecessors(s, idx));
indices.add(idx); // Also add the index corresponding to the requested statement index.
Collections.sort(indices);
Map<Integer, Integer> newIdx = new LinkedHashMap<Integer, Integer>();
for (int j = 0; j < indices.size(); j++) {
newIdx.put(indices.get(j), j);
}
Sequence news = new Sequence();
for (int i = 0; i < indices.size(); i++) {
int oldidx = indices.get(i);
List<Variable> oldins = s.getInputs(oldidx);
List<Variable> newins = new ArrayList<Variable>(oldins.size());
for (Variable oldv : oldins) {
newins.add(news.getVariable(newIdx.get(oldv.index)));
}
news = news.extend(s.getStatementKind(oldidx), newins);
}
return news;
}
public static Sequence getLongestDepSetSubSequence(Sequence s) {
BitSet indices = longestDepSet(s, s.size() - 1);
int length = indices.length();
assert indices.get(length - 1);
Map<Integer, Integer> newIdx = new LinkedHashMap<Integer, Integer>();
int count = 0;
for (int i = 0; i < length; i++) {
if (!indices.get(i)) continue;
newIdx.put(i, count++);
}
Sequence news = new Sequence();
for (int i = 0; i < length; i++) {
if (!indices.get(i)) continue;
List<Variable> oldins = s.getInputs(i);
List<Variable> newins = new ArrayList<Variable>(oldins.size());
for (Variable oldv : oldins) {
newins.add(news.getVariable(newIdx.get(oldv.index)));
}
news = news.extend(s.getStatementKind(i), newins);
}
return news;
}